Pressurizing construction

ABSTRACT

An assembly for use with ink-containing cartridges of writing instruments whereby a low-order pressure during writing automatically increases pressure on the ink in the cartridge while permitting the cartridge to vent to atmosphere when not in use. The assembly includes a movable element carrying a flexible and resilient washer, normally biased into venting position and provides air channels and sealing zones coacting with the washer for pressurizing. A writing instrument including a barrel and a project-retract mechanism as well as an ink-containing cartridge having a writing tip is also disclosed with the cartridge being provided with the assembly.

United States Patent Inventor Appl. No.

Filed Patented Assignee PRESSURIZIN G CONSTRUCTION References Cited Primary Examiner-Lawrence Charles Att0rneyMiketta, Glenny, Poms and Smith ABSTRACT: An assembly for use with ink-containing cartridges of writing instruments whereby a low-order pressure during writing automatically increases pressure on the ink in the cartridge while permitting the cartridge to vent to atmosphere when not in use. The assembly includes a movable 13 claimsnnrawing Figs element carrying a flexible and resilient washer, normally U.S.Cl 4011/101, biased into venting position and provides air channels and 401/1 sealing zones coacting with the washer for pressurizing. A lnt.Cl. ..B43k 24/08, writing instrument including a barrel and a project-retract B431: 7/02 mechanism as well as an ink-containing cartridge having a Field of Search 401/ 187, writing tip is also disclosed with the cartridge being provided 188, 112 with the assembly.

L I n I 50 -a0- i ,1 1 t 53 Maw 5a =-w PATENTEnum 19 Ian 3, 5 1 4 24 SHEET 3 OF 3 PRESSURIZING CONSTRUCTION Most writing instruments employ fillers or cartridges containing ink, the ink being fed to a writing tip by one or more capillary channels. The writing tip may be made of porous material or it may be of the ballpoint type. In many instances, the ink compositions employed are fairly viscous and the act of writing on a vertical surface or on a surface which faces downwardly, cannot be continued for more than a few seconds unless a pressure slightly greater than atmospheric is being exerted upon the body of ink in the cartridge. An effective pressurizing assembly capable of installation in any of the usual tubular ink reservoir cartridges used in writing instruments (particularly of the retractable ballpoint type) is disclosed in U.S. Pat. No. 3,420,610. The device there disclosed maintains the rear portion of the cartridge (above the ink) vented to atmosphere at all times whether the instrument is in the retracted or projected positions, but whenever the writing tip is actually used in writing, the pressure of the air within the rear portion of the cartridge is slightly increased thereby insuring immediate writing and permitting writing in all positions of the instrument, even when inverted.

The present invention may be said to constitute an improvement upon devices of the character disclosed in U.S. Pat. No. 3,420,610. As hereinafter described in detail, the present invention changes and modifies the air channels, provides sealing zones which coact with resilient elements for pressurizing very effectively, insures the production of long lasting and efficiently operating devices whereby variations in the resilient characteristics of the deformable or flexible element are minimized and the standardized, acceptable instrument is made available to the public in tremendous quantities. Moreover, the pressurizing efiect is attained by a very minute axial movement of the ink cartridge with respect to the barrel of the writing instrument containing the cartridge so that the user need not change or modify his normal writing habits.

FIG. 3 is a view of a portion of FIG. 2 showing the position of the improved pressure control assembly under pressure during writing;

FIG. 4 is a transverse section taken along the plane IV-lV of FIG. 2;

FIG. 5 is an enlarged longitudinal section of a modified form of pressure control assembly shown in a nonwriting position;

FIG. 6 illustrates the position of the elements of FIG. 5 during writing;

Moreover, the construction operates when the instrument is used at various angles to the writing surface and response to very light writing pressure, while still being able to withstand the abuse of a writer who bears down heavily on his writing instrument.

One of the characteristic features of the present invention lies in the provision of air channels having walls including the stem of the movable element and of the resilient or elastic element, this channel communicating the space forwardly of the washer with the space adjacent the head of the axially movable element prior to flexure of the washer caused by movement of the movable element against the biasing means and the pressurizing assembly. Moreover, in accordance with the present invention, the sealing surface upon which the resilient washer is seated for pressurization is virtually frustoconical and preferably a surface of revolution of a curved line, such as a convex surface. As a result, the strain on the resilient washer is much more effectively distributed and its life increased, par ticularly since the air channel is centrally located. The air channel being sealed may comprise an axially extending openended groove formed in the washer, said groove being open to the axial port in said washer or it may be fonned directly in the stem of the axially movable element. Moreover, the stem preferably carries a thrust means spaced from the sealing zone surface so as to position the flexible washer on the stem and relieve the washer from the direct thrust of the biasing means. These various constructional features cooperate to give rise to unexpectedly valuable results.

Although the invention is applicable to writing instruments of various types, as previously indicated, it will be specifically described in its adaptation to a writing instrument of the ballpoint type and for purposes of illustration, reference will be had to the appended drawings in which:

FIG. I is a longitudinal section of a retractable ballpoint pen containing a cartridge provided with a self-pressurizing assembly of the present invention, the cartridge being shown in projecting, nonwriting position;

FIG. 2 is an enlarged longitudinal sectional view taken along the plane II-ll of FIG. 1 and showing an improved pressure control assembly in projecting, nonwriting position;

FIG. 7 is a perspective view of the washer-shaped deformable element used in the devices of FIGS. 2-6;

FIG. 8 is a longitudinal section of a second modified form of the improved pressure control assembly in a cartridge, shown in the nonwriting position;

FIG. 9 is a view of FIG. 8 but with the control assembly shown under writing pressure;

FIG. 10 is a transverse section taken along plane X)( of FIG. 8; and

FIG. 1111 is a perspective view of one form of resilient washer-shaped element adapted for use in the constructions illustrated in FIGS. 8, 9 and 110.

The exemplary form of writing instrument illustrated in FIG. I may include a hollow housing or barrel 2 preferably composed of upper and lower portions suitably connected together for ready removal and replacement of cartridges. The upper end portion of the barrel may contain any suitable form of project and retract mechanism such as that indicated generally at 3, which may be actuated by manual depression of the end plunger 4. The barrel is shown carrying a Jumbo"- type ink-containing cartridge 10 of substantially uniform external diameter except for a forward end of reduced diameter leading to the writing tip 5. Cartridges of this type are generally biased into retracted position by means of a biasing spring 6. The cartridge is shown provided with a self-pressurizing assembly of the present invention generally indicated at 20, such assembly being carried by the rear end of the cartridge and including a rearward extension 49. This extension is shown cooperating with a Wobbler 7 which, upon actuation of the pushbutton 4, may be caused to engage longitudinally displaced shoulders 8 and 9 so as to place the cartridge either in projecting position as illustrated, or in retracted position. The cartridge 10 contains a body of ink and, in many cases, a small quantity of greaselike follower 16 on the surface of such body of ink, thereby preventing oxidation, evaporation and other changes which might occur by reaction of the air above the ink with the ink itself.

It is to be understood that the present invention is not limited to its use in the particular form of pen illustrated in FIG. 1, nor to the use of any particular type of retraction mechanism, size of ink cartridge, whether such cartridge contains or does not contain a porous or absorbent filler, the character of the ink employed, the construction of the tip 5 and other such details. It is desirable that the pressurizing assembly of the invention be employed with ink-containing cartridges which are used in various types of writing instruments since the presence of the pressurizing assembly of this invention on such cartridge permits its use in now existing writing instruments, interchangeably with older cartridges not equipped with the pressurizing assembly.

The pressurizing control assembly 20 comprises a cupshaped adapter which may be in one part or two parts, as illustrated in FIG. 2 wherein a thin outer metallic, cylindrical shell 21 carries an inner hollow cup-shaped element 22 having a transversely extending bottom 23 provided with an axial bore 24. The outer shell 21 may be provided with a rear, outwardly extending flange 21a which, when the assembly is press-fitted into the rearwardly open end of cartridge barrel l2, positively positions the assembly at the rear of the cartridge. Extending into the cup-shaped element 22 is an axially movable element having a headed or piston end 50 which may loosely fit into the cup or cartridge and which has the rearward extension 49 and a forwardly extending stem end generally indicated at 51, whose forward end may loosely extend through the port 24. This forward end 511 may terminate in ears 52 which limit axial movement of the movable element in a rearward direction by cooperating with the external surface of the bottom wall 23.

In accordance with the present invention, the headed end of the axially movable cylinder is provided with a forwardly directed, virtually frustoconical zone surface 53 which extends outwardly from the stem 51. Carried by the stem 51 adjacent such forwardly facing zone surface is an axially ported, disklike, deformable, resilient, elastic washerlike member 54. Its axial port is indicated at 55 (see FIG. 4). The washer 54 is smaller in its external diameter than the internal diameter of the upper portion of the cup adapter 21 and the lower surface of the resilient washer 54 lies in a substantially transverse plane and normally rests upon a rearwardly facing shoulder 25 of the cup 22. The stem 51 preferably carries a thrust means 56 which positions the flexible washer 54 on the stem 51 and, at the same time, receives the rearward thrust of a biasing spring 57 contained within the adapter and bearing against the transverse bottom wall 23 thereof.

Means are now provided whereby the space within the adapter forwardly of the resilient washer 54 is placed in communication with the ambient atmosphere and the space rearwardly of the resilient washer. In the various forms of the device illustrated, channels are provided having walls which include the stem 51 and the washer. In the form of device shown in FIGS. 2, 3, 4 and 5, the air channels are formed directly in the stem 51 and are indicated at 58 and 58'.

As shown in the drawings, the channels 58 and 58' have an inner wall which is a part of the stem and an outer wall which comprises a portion of the axial wall of the aperture 55 through the washer 54. The upper ends of these channels 58 and 58 communicate by way of radially and outwardly extending channel portions which terminate in ports 59 and 59 formed in the zone surface 53 adjacent the stem. The lower ends of channels 58 and 58' also communicate with radially extending channel portions which are formed in the thrust means 56 and permit air which is within the cup and in communication with the air above the body of ink in the cartridge itself by the Space provided between the forwardly extending stem 51 loosely fitting in the axial port 24 of the bottom wall of the cup, to pass through the channels and be placed into communication through the ports 59 and 59' with ambient atmosphere available around the head 50 within the barrel, and atmosphere ambient the barrel. One or more grooves such as 50 may be fonned in head 50 to insure such venting.

It is to be remembered that the retraction spring 6 is generally slightly weaker than the biasing spring 57 so that the entire cartridge together with its pressurizing adapter may move against and be in contact with the wobbler 7 of the retraction mechanism at all times. The elements of the pressurizing assembly shown in FIG. 2 are in the position indicated therein whether the writing tip of the cartridge is in projected or retracted position. In FIG. 2, the device is shown inthe projected but nonwriting position and it will be evident that the interior of the cartridge is vented past the forward position of the stem 51 into the adapter and then by means of the channels 58 and 58' to ambient atmosphere.

When, however, the writing instrument is actually engaged in writing upon a sheet of paper or the like, the pressure of the writing tip upon the paper is transmitted through the cartridge and relative motion takes place between the cartridge and adapter and the axially movable element including the stem 51, head 50 and rearward extension 49. During such writing, the primary elements of the adapter assume the position indicated in FIG. 3 and it will be noted that the resilient deformable washerlike disk 54 has been flexed so that its upper surface contacts the zone surface 53 and seals the ports 59 and 59' which lead to the longitudinally extending air channels 58 and 58'. The lower surface of the resilient element 54 retains contact with the upwardly facing annular shoulder 25 and therefore a slight amount of pressure is generated in the air trapped below this resilient washerlike pressurizing element and such pressure is distributed to the air trapped above the body of ink in the cartridge itself. Since during writing a writing tip is repeatedly applied to and raised from the surface upon which the writing is being accomplished, there is a continuous series of pulsations or pressure pulsesapplied to the surface of the body of ink within the cartridge.

Pressurization by the use of a construction herein described occurs at a writing pressure load which is 30 percent to 40 percent lower than the pressure required with other arrangements. Moreover, the differential pressures between the springs employed (such as the retraction spring 6 and the biasing spring 57) are not as critical. Furthermore, the axial movement required to cause sealing and pressurization is extremely minor and the user of a pen provided with the device of this invention is not cognizant of any material change in the feel of his writing instrument. The strain and stress forces generated in the resilient axially ported washerlike element are also very minor and it has been found that the life of these elements is greatly increased by the construction herein disclosed.

Attention is called to the fact that the zone surface 53 is said to be virtually frustoconical and forwardly directed. In FIGS. 2 and 3, this forwardly directed zone surface is shown generated by a curved line so as to present a forwardly directed, slightly convex surface. However, said surface may be slightly concave as indicated in FIGS. 5 and 6 or it may be truly conical as in FIGS. 8 and 9. The same number 53 is applied to all three forms of such zone surface for purposes of simplification.

In FIGS. 5 and 6 wherein the forwardly directed zone surface is concave, the air channels 58 and 58' are formed in the stem as in FIG. 2 and communicate with channel portions opening into ports in the zone surface as in FIG. 2 and extending downwardly or forwardly through the thrust means 56. However in FIGS. 5 and 6 it will be noted that the outer edge portion of the resilient elastic and flexible washer element here shown as 54 is grasped in an annular groove formed on the inner surface of the cup 22. In either projected or retracted but nonwriting positions, the elements assume the form illustrated in FIG. 5 and the interior of the cartridge is vented to the atmosphere. However, under the influence of I writing pressure, relative motion takes place between the stem of the assembly and the cartridge itself into the position indicated in FIG. 6 and the channel portions associated'with radial ports 59 are sealed and the trapped atmosphere forwardly of the resilient element is pressurized.

The modification illustrated in FIGS. 8. 9, l0 and 11 employs an elastic resilient axially ported washerlike member 54" but the walls of the axial port 55 are now grooved as indicated at 68 and 68'. The elastic element 54 fits snugly around the stem 51" between the zone surface 53 and the thrust means 56 but the grooves 68 and 68' now form channels whose walls include a portion of the external surface of the stem 51" and the walls of the groove in the washer 54". It may be noted that the stem 51" is not longitudinally grooved and neither the zone surface nor the thrust means need to have channels or air groove portions formed therein. The downwardly or forwardly facing zone surface 53 may be frustoconical, slightly concave or slightly convex although the convex surface is preferred. It is also to be noted that in the modification illustrated in FIGS. 8 and 9, the cup-shaped adapter is provided with an outwardly flaring lip which now provides the upwardly facing shoulder 25' and, in its normal position, (not under writing pressure) the lower face of the resilient washerlike element 54" is in contact with the rearwardly facing stop shoulder 25' as illustrated in FIG. 8. Under writing pressure and relative movement between the cartridge and its pressurizing adapter and the stem thereof, the channels 68 and 68 are closed by contact with the forwardly facing zone surface. It is understood that these grooves or channels 68 and 68' have a shorter depth than the radial extent of the zone surface.

I claim:

1. In a pressurizing control assembly for installation at the rear end of an ink reservoir cartridge of a writing instrument, said assembly including a cylindrical cup having a rearwardly facing open end, an annular rearwardly facing shoulder adjacent said open end and a forwardly disposed axially ported wall, an axially movable element having a front stem end loosely extending through said ported wall and a headed rear end extending beyond the rear end of such cartridge, means for biasing said element rearwardly and means carried by the stem to limit said rearward bias movement, the provision of:

a forwardly facing, virtually frustoconical zone surface on' the head of the axially movable element, extending outwardly from said stern;

an elastic, resilient axially ported washer carried by said stern, said washer being normally planar to contact said rearwardly facing annular shoulder, said washer being adapted to contact the initial central portion of the virtually frustoconical zone surface of the head upon movement of the movable element against biasing means and upon flexure of the washer;

and an air channel having walls including said stern and washer and communicating the space forwardly of the washer with the space adjacent the head and zone surface prior to flexure of said washer, said washer closing said channel upon flexure of the washer.

2. A pressurizing control assembly as stated in claim ll wherein the forwardly facing zone surface of the head is a surface of revolution of a curved line.

3. A pressurizing control assembly as stated in claim ll wherein the forwardly facing zone surface of the head is a convex surface.

4. A pressurizing control assembly as stated in claim ll, wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and the thrust means.

5. A pressurizing control assembly as stated in claim 1 wherein the air channel comprises an axially extending, openended groove formed in the washer, said groove being open to the axial port in said washer.

6. A pressurizing control assembly as stated in claim 1 wherein the air channel is formed in said stem and communicates with a port in the central marginal edge portion of the zone surface adjacent said stem.

7. A pressurizing control assembly as stated in claim 5 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.

8. A pressurizing control assembly as stated in claim 3 wherein the air channel comprises an axially extending openended groove formed in the washer, said groove being open to the axial port of said washer.

9. A pressurizing control assembly as stated in claim 3 wherein the air channel is formed in said stern and communicates with a port in the central marginal edge portion of the zone surface adjacent said stem.

10. A pressurizing control assembly as stated in claim wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.

11. in a writing instrument including a barrel provided with a project-retract mechanism and an ink-containing cartridge having a writing tip arranged to be projected and retracted by said mechanism, the rear end of said cartridge carrying a pressurizing assembly including a ported wall positioned transversely within and spaced from the rear end of the cartridge, a rearwardly facing annular shoulder, an axially movable element having a front stem end loosely extending through said ported wall and a headed rear end extending beyond the rear end of said cartridge, means for biasing said element rearwardly and means carried by the stem to limit said rearward biased movement, the provision of:

a forwardly facing, virtually frustoconical zone surface on the head of the axially movable element, extending outwardly from said stem; an elastic, resilient axially ported washer carried by said stem, said washer being normally planar to contact said rearwardly facing annular shoulder, sad washer being adapted to contact the initial central marginal portion of the virtually conical zone surface of the head upon move ment of the movable element against biasing means and upon flexure of the washer;

and an air channel having walls including said stern and washer and communicating the space forwardly of the washer with the space adjacent the head prior to flexure of said washer.

12. A pressurizing control assembly as stated in claim 6 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.

13. A pressurizing control assembly 5 stated in claim 9 wherein the stem of the axially movable: element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means. 

1. In a pressurizing control assembly for installation at the rear end of an ink reservoir cartridge of a writing instrument, said assembly including a cylindrical cup having a rearwardly facing open end, an annular rearwardly facing shoulder adjacent said open end and a forwardly disposed axially ported wall, an axially movable element having a front stem end loosely extending through said ported wall and a headed rear end extending beyond the rear end of such cartridge, means for biasing said element rearwardly and means carried by the stem to limit said rearward bias movement, the provision of: a forwardly facing, virtually frustoconical zone surface on the head of the axially movable element, extending outwardly from said stem; an elastic, resilient axially ported washer carried by said stem, said washer being normally planar to contact said rearwardly facing annular shoulder, said washer being adapted to contact the initial central portion of the virtually frustoconical zone surface of the head upon movement of the movable element against biasing means and upon flexure of the washer; and an air channel having walls including said stem and washer and communicating the space forwardly of the washer with the space adjacent the head and zone surface prior to flexure of said washer, said washer closing said channel upon flexure of the washer.
 2. A pressurizing control assembly as stated in claim 1 wherein the forwardly facing zone surface of the head is a surface of revolution of a curved line.
 3. A pressurizing control assembly as stated in claim 1 wherein the forwardly facing zone surface of the head is a convex surfacE.
 4. A pressurizing control assembly as stated in claim 1, wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and the thrust means.
 5. A pressurizing control assembly as stated in claim 1 wherein the air channel comprises an axially extending, open-ended groove formed in the washer, said groove being open to the axial port in said washer.
 6. A pressurizing control assembly as stated in claim 1 wherein the air channel is formed in said stem and communicates with a port in the central marginal edge portion of the zone surface adjacent said stem.
 7. A pressurizing control assembly as stated in claim 5 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.
 8. A pressurizing control assembly as stated in claim 3 wherein the air channel comprises an axially extending open-ended groove formed in the washer, said groove being open to the axial port of said washer.
 9. A pressurizing control assembly as stated in claim 3 wherein the air channel is formed in said stem and communicates with a port in the central marginal edge portion of the zone surface adjacent said stem.
 10. A pressurizing control assembly as stated in claim 8 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.
 11. In a writing instrument including a barrel provided with a project-retract mechanism and an ink-containing cartridge having a writing tip arranged to be projected and retracted by said mechanism, the rear end of said cartridge carrying a pressurizing assembly including a ported wall positioned transversely within and spaced from the rear end of the cartridge, a rearwardly facing annular shoulder, an axially movable element having a front stem end loosely extending through said ported wall and a headed rear end extending beyond the rear end of said cartridge, means for biasing said element rearwardly and means carried by the stem to limit said rearward biased movement, the provision of: a forwardly facing, virtually frustoconical zone surface on the head of the axially movable element, extending outwardly from said stem; an elastic, resilient axially ported washer carried by said stem, said washer being normally planar to contact said rearwardly facing annular shoulder, sad washer being adapted to contact the initial central marginal portion of the virtually conical zone surface of the head upon movement of the movable element against biasing means and upon flexure of the washer; and an air channel having walls including said stem and washer and communicating the space forwardly of the washer with the space adjacent the head prior to flexure of said washer.
 12. A pressurizing control assembly as stated in claim 6 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means.
 13. A pressurizing control assembly s stated in claim 9 wherein the stem of the axially movable element carries thrust means spaced from the zone surface to position the flexible washer on the stem, said biasing means being positioned between the ported wall and thrust means. 